Negative-U System of Carbon Vacancy in 4H-SiC

Using electron paramagnetic resonance (EPR), energy levels of the carbon vacancy (Vc) in 4H-SiC and its negative-U properties have been determined. Combining EPR and deep-level transient spectroscopy we show that the two most common defects in as-grown 4H-SiC—the Z[1/2] lifetime-limiting defect and the EH7 deep defect—are related to the double acceptor (2−|0) and single donor (0|+) levels of Vc, respectively.